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|
from django.db import models
class MastodonPaginator:
"""
Paginates in the Mastodon style (max_id, min_id, etc)
"""
def __init__(
self,
anchor_model: type[models.Model],
sort_attribute: str = "created",
default_limit: int = 20,
max_limit: int = 40,
):
self.anchor_model = anchor_model
self.sort_attribute = sort_attribute
self.default_limit = default_limit
self.max_limit = max_limit
def paginate(
self,
queryset,
min_id: str | None,
max_id: str | None,
since_id: str | None,
limit: int | None,
):
if max_id:
try:
anchor = self.anchor_model.objects.get(pk=max_id)
except self.anchor_model.DoesNotExist:
return []
queryset = queryset.filter(
**{self.sort_attribute + "__lt": getattr(anchor, self.sort_attribute)}
)
if since_id:
try:
anchor = self.anchor_model.objects.get(pk=since_id)
except self.anchor_model.DoesNotExist:
return []
queryset = queryset.filter(
**{self.sort_attribute + "__gt": getattr(anchor, self.sort_attribute)}
)
if min_id:
# Min ID requires items _immediately_ newer than specified, so we
# invert the ordering to accomodate
try:
anchor = self.anchor_model.objects.get(pk=min_id)
except self.anchor_model.DoesNotExist:
return []
queryset = queryset.filter(
**{self.sort_attribute + "__gt": getattr(anchor, self.sort_attribute)}
).order_by(self.sort_attribute)
else:
queryset = queryset.order_by("-" + self.sort_attribute)
return list(queryset[: min(limit or self.default_limit, self.max_limit)])
|
